Seizo Iwai

One-lung ventilation. The effect of positive end expiratory pressure to the nondependent and dependent lung

We applied positive end expiratory pressure to the nondependent, nonventilated lung, or both non‐dependent and dependent, ventilated lung during one lung anaesthesia, and compared the results to those obtained by other techniques, such as increasing the inspired oxygen concentration in the dependent lung, or insuffating with oxygen using positive end expiratory pressure in the nondependent lung. Our study suggests that arterial oxygenation and intrapulmonary shunt can be lessened during one lung ventilation by continuous oxygen insufflation of the nondependent lung at 0.98 kPa positive end expiratory pressure while the dependent lung is ventilated with 0.49 kPa positive end expiratory pressure.

The effects of various peptides on the isolated pulmonary artery

Helical strips of pulmonary arteries from rabbits were tested for their responses to the following peptides: neuropeptide Y (NPY), vasoactive intestinal polypeptide (VIP), substance P (SP), cholecystokinin-octapeptide (CCK), somatostatin (SS), bombesin, neurotensin and gastrin. SP, in the absence of active base-tension, and NPY both induced concentration-dependent contractions, while VIP and SP, in the presence of active base-tone, and CCK induced relaxation. The pD2 (-log ED50) was in the order of NPY greater than SP and SP greater than CCK greater than VIP. SS, bombesin, NT and gastrin had no effect. These findings suggest peptidergic involvement in the vessels.

Plasma cortisol levels in paediatric anaesthesia

We measured plasma cortisol levels during surgery in seven neonates within ten days after birth and in 14 infants ranging in age from three months to 11 months. The 14 infants were divided into two groups; Group I included eight infants in whom general anaesthesia was maintained with oxygen, nitrous oxide and a muscle relaxant, Group II, six infants in whom general anaesthesia was maintained with oxygen, nitrous oxide, halothane and a muscle relaxant. In the neonates, the changes in mean plasma cortisol levels during anaesthesia were not statistically significant. In both Group I and Group II infants, the mean cortisol levels gradually rose during anaesthesia, but the initial rise in plasma cortisol levels was suppressed in the patients who received halothane.RésuméLes niveaux plasmatiques de cortisot ont été mesurés chez sept nouveau-nés à moins de dix jours d’âge et chez 14 enfants de trois à II mois. Ces enfants ont été répartis en deux groupes: le groupe I - huit enfants sous anesthésie générale à l’oxygène-protoxyde et un myorésolutifet le groupe II - six enfants chez qui l’anesthésie générale a été entretenue avec de l’oxygène-protoxyde d’azote, de l’halothane et un myo-résolutif.Chez les nouveau-nés, des changements de la concentration plasmatique moyenne du cortisol n’étaient pas statistiquement significatifs. Chez les patients des groupes I et II, les niveaux moyens de cortisot plasmatique ont augmenté graduellement durant l’anesthésie mais chez ceux qui ont reçu de l’halothane, l’augmentation initiale du cortisol plasmatique a été supprimée.

Eventration of the Diaphragm in Infants and Children

ABSTRACT. The study reviews 18 infants and children with eventration of the diaphragm who were treated over a period of eight years. The affected diaphragm and pulmonary tissue were examined by light and electron microscopy. The 18 patients, ranging in age from 10 days to 6 years, were divided according to Thomas’classification into a group with the congenital (10 patients) and a group with the acquired type (8 patients). Fifteen of these patients underwent surgery with diaphragmatic plication. On microscopic examination, biopsies of the lung showed atelectasis and pneumonia. These pathological changes became increasingly diffuse and severe with age. The diaphragm in patients with the congenital type of eventration was occupied by diffuse fibroelastic tissue. In patients with the acquired type, the cross‐striated muscles of the diaphragm showed degenerative changes such as fragmentation, and interstitial fibrosis of the diaphragm became prominent with age. The results of this clinical study sugget that, in order to reduce the pathological changes in the lung, early surgical plication should be performed even in patients with the acquired type, if respiratory and digestive symptoms are noted.

Relaxant effect of dopamine on isolated rabbit pulmonary artery.

In rabbit pulmonary artery, dopamine (10(-11)-10(-5) M) produced a concentration-dependent relaxation of the arterial strips contracted with prostaglandin F2 alpha (PGF2 alpha) in the presence of prazosin (10(-6) M), yohimbine (10(-6) M), propranolol (10(-6) M), and methysergide (10(-6) M). SKF38393, an agonist for D1 or DA1 dopamine receptor, mimicked partially the concentration-response curve for dopamine, whereas LY171555 and apomorphine did not. The order of potency of dopamine antagonists on the inhibitory effect was: cis-flupenthixol greater than bulbo-capnine greater than metoclopramide greater than haloperidol. Sulpiride was inactive. Cis-flupenthixol did not block the relaxation induced by acetylcholine, adenosine, and papaverine. In the arterial strips of the rabbits pretreated with 6-hydroxydopamine, the concentration-response curve for dopamine was similar to that in non-treated rabbits. Thus it is concluded that a specific dopamine receptor is located on the postsynaptic muscle membrane of the rabbit pulmonary artery.

Endothelium-dependent relaxation in isolated pulmonary arteries from rabbits exposed to hyperoxia

The effects of hyperoxia and superoxide dismutase (SOD) administration on endothelium-dependent relaxation induced by acetylcholine in isolated rabbit pulmonary artery (PA) preparations were examined. Relaxation responses to papaverine, and contractile responses to KCl and norepinephrine were also assessed using a bioassay technique. Prolonged hyperoxia in rabbits for 3 days produced loss of endothelium-dependent relaxation of the PA, and significant attentuation of contractile response to KCl and relaxation response to papaverine. These changes were prevented by subcutaneous SOD administration. Histological examination using light and electron microscopy revealed focal edema, destruction, and detachment of the PA endothelium in the PA strip preparations from these rabbits. Thus, it is concluded that a high concentration of oxygen exposure in rabbits for 3 days produces not only histological damage in the PA endothelium, but also causes impairment of vascular reactivity to constricting and relaxing agents. Subcutaneous SOD administration prevented oxygen-induced PA damage.

Effect of Dopamine on Plasma Growth Hormone and Prolactin Concentrations under Anaesthesia

Five patients with acromegaly and five patients with prolactinoma undergoing general anaesthesia were studied. Concentrations of plasma growth hormone in patients with acromegaly and concentrations of plasma prolactin in patients with prolactinoma were measured before anaesthesia, when 250 mg levodopa was administered orally, and after anaesthesia when dopamine was infused intravenously at a rate of 5 μg/kg-min. There was no difference in hormonal (growth hormone or prolactin) response to either treatment in the anaesthetized and the awake states. These findings indicate that the functioning of dopamine receptors in the anterior pituitary is not affected by anaesthesia.

Plasma levels of vitamin E and lipoperoxide during paediatric anaesthesia

We measured plasma levels of vitamin E (total tocopherol) and lipoperoxide in seventeen neonates (<10 days), twenty infants (1-12 months) and ten children (1-5 years) during anaesthesia.The seventeen neonates were randomly divided into two groups; seven who received 30mg.kg-1 of α-tocopheryl acetate intramuscularly before anaesthesia and ten who did not. The 20 infants were divided into three groups: Group 1 : eight infants who did not receive vitamin E; Group 2: six who received 30mg.kg-1 of α-tocopheryl acetate orally for three days before anaesthesia; Group 3: six who received 30mg.kg-1 of α-tocopheryl acetate intramuscularly three hours before anaesthesia.In the neonates who did not receive α-tocopheryl acetate, plasma vitamin E and lipoperoxide levels were unchanged following surgery. In Group I infants, plasma vitamin E levels decreased (p < 0.05) and plasma tipoperoxide levels increased (p < 0.05).In both neonates who received vitamin E and Group 3 infants the mean plasma vitamin E levels increased significantly (p < 0.05) fo follwing surgery. In Group 2 infants, the levels of plasma vitamin E before surgery were high, as compared to the other groups: however, plasma vitamin E levels decreased following surgery. In the children, the plasma vitamin E levels were unchanged, while the plasma lipoperoxide levels decreased significantly (p < 0.05) during anaesthesia.It is suggested from our studies that plasma vitamin E levels decrease and plasma lipoperoxide levels increase during anaesthesia and surgery in infants; however, those levels are unchanged in neonates.RésuméOn a mesuré le niveau plasmatique de la vitamine E (tocophérol total) et du lipoperoxide chez 17 nouveau-nés (<l0 jours), 20 nourrissons (1-12 mois) et dix enfants (un à cinq ans) pendant l’anesthésie.Les 17 nouveau-nés ont été divisés au hasard en deux groupes; sept ont reçu 30mg·kg-1 de α-tocophéryl acétate par vole intramusculaire avant l’anesthdsie el dix n’en ont pas reçu. Les 20 nourrissons ont été divisés en trois groupes: groupe 1 : huit nourrissons qui n’ont pas reçu de vitamine E; groupe 2: six qui ont reçu 30mg·kg-1 de α.tocophéryl acétate par vole orale avant l’anesthésie; groupe 3: six au ont reçu 30mg·kg-1 de α-tocophéryl acétate par voie intramusculaire avant l’anesthésie.Chez les nouveau-nés et le groupe 1 des nourrissons qui n’ont pas reçu de α-tocophéryl acétate, le niveau plasmatique de la vitamine E a diminué après la chirurgie et le niveau plasmatique du lipoperoxide a augmenté.Tant chez les groupe de nouveau-nés ayant reçu la vitamine E que chez le groupe 3 des nourrissons, le niveau plasmatique moyen de la vitamine E a augmenté significativement (p < 0.05) après la chirurgie. Pour le groupe 2 des nourrissons, le niveau plasmatique de la vitamine E avant la chirurgie était élevé, comparativement aux autres groupes; cependant le niveau plasmatique de la vitamine E a diminué après la chirurgie.Chez les enfants, le niveau ptasmatique de la vitamine E a augmenté significativement et le niveau plasmatique du lipoperoxide a diminué significativement (p < 0.05) pendant l’anesthésie.Il ressort de nos études que le niveau plasmatique de la vitamine E diminue et le niveau plasmatique du lipoperoxide augmente pendant l’anesthésie et la chirurgie, spécialement chez les nouveaux-nés et les nourrissons.

Maturation-Related Changes in Dopamine-Induced Relaxation of Isolated Rabbit Pulmonary Artery

ABSTRACT: Studies were performed on isolated pulmonary arterial segments to investigate dopamine receptor-mediated relaxant effects at different times during development. Dopamine receptor-mediated relaxant effects can only be observed when vessels are precontracted with prostaglandin F2α and in the presence of α1, α2, and serotonergic blockade. Helical strips of pulmonary arteries from rabbits of different ages (2, 7, 14, 30, and 90 days), partially precontracted by prostaglandin F2α were tested for their responses to dopamine in the presence of prazosin (10-6 M), yohimbin (10-6 M), propranolol (10-6 M), and methysergide (10-6 M). Strips from 2– and 7-day-old rabbits were not induced to relax by dopamine, whereas those from 14–, 30–, and 90-day-old animals, after cumulative application of dopamine, underwent concentration-dependent relaxation. Dopamine (half the maximum response) concentration decreased during the development of rabbits from 14 to 90 days old. Mean values for apparent dopamine ED50 (half the maximum response) concentrations in the arteries of 14–, 30–, and 90-day old animals were 4.94 ± 0.40, 2.02 ± 0.30, and 0.113 ± 0.028 μM, respectively. The effects of various dopamine antagonists on dopamine-induced relaxation were not markedly different at different ages. These findings indicate that dopamine receptor function is not fully developed in the pulmonary arteries of newborn rabbits, but matures as the age of the rabbit increases.

The effect of hyperoxia on the lungs of rats deficient in essential fatty acids

Morphological alterations in the lungs of rats deficient in either or both of vitamin E and essential fatty acids were investigated after exposure to hyperoxia for 48 h. In rats deficient in both vitamin E and essential fatty acids, there was damage to type-2 alveolar cells observed as swollen mitochondria and bleb formation in the cytoplasm. None of these changes was found in rats deficient in only one of these substances. Hyperoxia in rats deficient in both substance also caused destruction of the capillary endothelial cells and edema in the interstitium. The lungs of rats deficient in only one of the substances showed some edema in the capillary endothelial cells, but not destruction, and less interstitial edema. These findings suggest that simultaneous deficiency in vitamin E and essential fatty acids facilitates lung damage in rats exposed to hyperoxia.